Connect SHDN to +5.
Get rid of this, is taken care of by SPI library
const int sclkPin = 13;
Get rid of these - not needed with software command 0100 being used:
delay(2);
digitalWrite(sclkPin,HIGH);//Data clocked rising edge
delay(2);
digitalWrite(sclkPin,LOW);
digitalWrite(ldacPin, LOW);//Force update
Add this in setup:
pinMode (ssPin, OUTPUT);
digitalWrite (ssPIN, HIGH);
Add this after the SPI.transfers
digitalWrite (ssPin, HIGH);